i belong to st category and found form of sc/ st certificate on pnb site for joining formalities. when i went to tehsildar for attestation , he denied to attest.. i already have cast certificate . pls help

M an aspiring candidate for PSU bank, planning to give the IBPS exam next year. I will have to give preference for the banks while filling up the form.
I have seen many people opting for PNB n BOB. My question is what makes pnb n Bob the first preference for most candidates.?
Do they pay higher (in hand)?
Better promotion?
Better work culture?
Better postings?
N is it better than Exim n Ecgc?
Thank you

EXIM and ECGC pay the highest , also they have 5 days in a week work culture. Apart from them , BON , PNB , and Canara are the biggest banks, and they have better allowances. Also people from north india prefer these banks because most of their branches are in north (BOB and PNB) .